U.S. Pat. No. 8,101,422 (Srinivasan et al.) purports to disclose a multidimensional ion chromatography apparatus for analyzing a sample in the first dimension and then transferring a selected portion of the eluent to a second dimension for analysis. The system is capable of concentrating or purifying certain components prior to the second dimension injection. The capability of their analysis is limited to two dimensions. Additionally, more than one set of pumps were used to support their claims for the two-dimensional analysis. Extension of the technology to higher dimensions could require multiple number of liquid moving devices (pumps) and more than one detector.
U.S. Pat. No. 6,802,967 (Masuda et al.) purports to disclose a multi-dimensional liquid chromatography system for storing the analyte(s) from the first dimension run and re-injecting the analyte(s) into the second dimension column(s). The system is also capable of de-salting the sample while in storage using solvents other than the mobile phase solvents. Each dimension has a dedicated detection device. The design is equipped with two detectors and consequently, can not be extended beyond two dimensions for analytical applications.
US Pat. No. 20060157647 A1 (Siuzdak et al.) purports to disclose a multidimensional liquid chromatography system for moving a sample chromatographed from the first dimension alternatingly through a set of two columns for mass spectrometric and NMR spectroscopic analyses. According to their claims, a first dimension column was alternatingly set in fluid communications with two different detectors and the data obtained from both channels are claimed to constitute a dataset for a three-dimensional analysis. The setup is not capable of re-injecting an analyte from the second dimension into the third dimension.